How to Make High Resolution Images on Your Computer or Smartphone

Increase the resolution of any photo on your PC, Mac, or mobile device

Hands framing a cloud against a blue sky.

Grant Faint/Getty Images

Taking a digital image and making it smaller is a relatively simple task, but knowing how to increase the resolution of an image is a little more challenging. Fortunately, there are a few things you can do to improve the quality of a blown-up photo.

This article provides instructions for desktop Gimp 2.10 which is available for Windows, macOS, and Linux. It also includes instructions for macOS X Preview (macOS 10.3 or later) and Image Save, which requires iOS 9.0 or later.

Principles of Making a Picture Higher Resolution

It’s important to be clear about what we mean when we talk about increasing the resolution of an image. Resolution correlates to the number of pixels in a digital picture. The more pixels you have, the higher the image’s resolution.

To improve a picture’s resolution, we first increase the size of it, then we make sure it has the optimal pixel density. The end result is a larger image, but it will likely look less sharp than the original picture. The bigger you make your image, the more you’ll see a difference in sharpness. Again, we’re simply making the picture bigger and adding pixels, not more detail.

As a rule of thumb, 300 pixels-per-inch is the accepted standard for printed images.

To mitigate this you should:

  • Avoid a significant increase in size: Obviously, all images are different, but if you decide to increase the dimensions by more than 30 percent or 40 percent, you’ll likely notice a loss of sharpness.
  • Use sharpen tools when available: Not all apps have them, but Gimp and Photoshop both include features for sharpening images. The final effect can sometimes seem unnatural, so its key to use them sparingly if you want to retain a similar look to your original picture.

How to Make High Resolution Images using Desktop Gimp

Gimp is a free, open source image editing tool available for Windows, macOS, and Linux. It offers broad support for a host of image formats making it ideal for this kind of task.

  1. Launch Gimp.

  2. Select File > Open.

    File > Open menu in Gimp for macOS
  3. This will launch the file picker. Locate your image and select Open.

    Open dialog box in Gimp for macOS
  4. Select the image tab.

    Image window in Gimp for macOS
  5. Press Ctrl+A (Windows) or command+A (Mac) to select the whole image.

  6. Remaining on the image tab, press Ctrl+C or Command+C to copy the image.

  7. Now we're going to create the higher resolution copy. Select File > New to open a new image template.

    File > New menu items in Gimp for macOS
  8. We need to make sure your final picture will have a resolution of 300 pixels-per-inch. To do this, select Advanced Options.

    Advanced options in Gimp for macOS

    You’ll see the pre-filled width and height match your current image. Don't change these values.

  9. The dialog box will expand, revealing the X and Y resolutions for the image. The boxes may already show the canvas is set to 300. If it isn't, adjust both the X and Y values to 300, then select OK.

    X and Y resolution fields in Gimp for macOS
  10. You'll now have a new image window which has the same dimensions as your original photo.

    New image window in Gimp for macOS
  11. Making sure you are working on the box for your new image, select Image > Canvas Size.

    File > Canvas Size menu item in Gimp for macOS
  12. Another dialog box will open. This is where we’ll adjust the canvas size.

    Image Canvas Size dialog box in Gimp for macOS
  13. Before you adjust the canvas width or height, ensure the chain icon to the right of both measurements is locked.

    Chain link icon in Gimp for macOS
  14. Enter your new desired image width, then press tab. You'll see the height automatically adjusts to match the image scale. In this example we’re going from just over 4000 pixels to 6000 pixels.

    Be sure to remember or note down your new dimensions. You'll need these again later.

  15. Select Resize.

    Resize button in Gimp for macOS
  16. Remaining in your new new image window, press Ctrl+V or Command+V to paste the image.

    Image pasted to new image window in Gimp.
  17. Drag the corner of your window (and zoom out if necessary) so you can clearly see all corners of your resized canvas. You'll notice the image is pasted in the center of your new image window at its original size.

    Pasted image zoomed out in Gimp.
  18. We now need to make the pasted image fully cover the new canvas size. First, go to the Layers window and select Floating Selection (Pasted Layer) if it's not already selected.

    Pasted Layer in Gimp for macOS
  19. Go to the Toolbox window on the left and select the Scale tool.

    Scale tool in Gimp for macOS
  20. Select your pasted image, and you'll see a scale guide appear as well as a scale dialog box. In the scale dialog box, ensure the chain icon is locked, then enter the same width value you used in step 13.

    Chain icon in scale dialog for Gimp in macOS
  21. You will see a preview of what your resized image will look like. If it looks good, select Scale.

    Scale button in Gimp for macOS
  22. Your image is now resampled at the newer size.

    Gimp resampled image.
  23. Before exporting your image, you can check the quality of it by zooming in. To do this, select View > Zoom, then choose your desired zoom level.

    Zoom menu in Gimp for macOS
  24. Once you're happy with the end result, go to the Layers window and right-click Floating Selection (Pasted Layer), then select Anchor Layer to lock it to the background.

    Anchor Layer in Gimp for macOS
  25. To export your image, select File > Export.

    Export menu in Gimp for macOS
  26. This will open a new dialog box. Choose where you want to save your resized image and name it. Then select Export.

    File name field in Save dialog in Gimp for macOS

    When naming your image, you can also set the file type by typing the extension. For example, calling your image "new_photo.png" will save it as a PNG file, or "new_photo.jpg" will save it as a JPEG.

  27. A final dialog box will appear, offering settings for your saved photo. To get the best possible final image quality, move the Compression Level slider to zero, then select Export.

    Compression level slider in Gimp for macOS
  28. Congratulations! You have increased the resolution of your image.

How to Increase the Resolution of an Image using macOS X Preview

Preview is a useful tool for viewing photos and PDFs on your Mac, but it also includes some handy image editing tools.

  1. Locate your image file, then right-click it and click Open with > Preview.

    Open with Preview on macOS
  2. Click the Markup Toolbar icon.

    Markup toolbar in Preview on macOS
  3. Click the Adjust Size icon.

    Adjust Size icon in Preview on macOS
  4. Adjust the width to your desired amount, then click OK. For this example, we're going to resize the picture from a width of 1000 pixels to 1300 pixels.

    Width and Height fields in Preview on macOS

    Ensure the lock icon is closed and "Resample Image" is checked.

  5. Your image will resize. Click File > Save to overwrite the original image or File > Export to save it as a new file.

    File > Save and File > Export menu items in Preview on macOS
  6. All done! Your resized image is now saved.

How to Increase the Resolution of an Image using Image Size for iPhone

Image Size for iOS is a photo editing tool that lets you also resize images. It's free, but you can choose to pay if you want to remove ads.

  1. Install and launch Image Size.

  2. Tap the main white box. Tap OK, to grant the app access to your photos, then tap the white box once more to open the image picker.

  3. Tap the image you want to resize.

    Image field, OK button, Moments in iOS
  4. Tap Choose to open your image.

  5. Tap the chain icon to lock your Width and Height values.

  6. Set your desired Width value, then tap Done. For this example we will scale the image up to 6000 pixels. Your Height value will automatically adjust as well.

    Choose, Chain icon, Width and Height, and Done buttons on iOS
  7. Your photo will resample at the new size; you can pinch and zoom to check the pixel quality.

  8. Tap the gear icon to view additional options. Ensure the output Quality slider is at 100 percent.

    Settings Gear, Print size correction factor buttons on iOS
  9. If you intend to print the image, you can smooth out some of the pixelation. To do this, tap the + icon to increase the Print size correction factor, then tap the back arrow to return to the main page.

  10. To save the final image, tap the save arrow.

    Save arrow and output message on iOS
  11. That's it! Your resized image is now saved to your Camera Roll.